HAP1 - Exercise 7
Follicle
- a structure formed from both epidermal and dermal cells. Its inner epithelial root sheath with two parts (internal and external) is enclosed by a thickened basement membrane, the glassy membrane, and a connective tissue root sheath which is essentially dermal tissue.
Epidermal Dendritic cells
- aka Langerhans cells -immunity
Keratin
- fibrous protein that gives the epidermis its durability and protective capabilities -connected to each other by desmosomes
Stratum Basale (basal layer)
-10% - 25% of the cells in this stratum are melanocytes - basal layer -rapid cell division -adequate diffusion
Stratum Spinosum (spiny layer)
-Largest layer of the epidermis. Under the stratum granulosum layer -contain thick weblike bundles of intermediate filaments made of pre keratin protein -adequate diffusion
Eccrine Glands
-aka merocrine sweat glands -distributed all over the body -produce clear perspiration consisting primarily of water, salts, and urea -heat regulating apparatus
Epidermis
-avascular -keratinized stratified squamous -4 distinct cell types and 4/5 distinct layers
Reticular Layer
-deepest skin layer -dense irregular CT and contains many arteries and veins. sweat and sebaceous glands, and pressure receptors (pacinian corpuscles)
Dermis
-dense irregular CT making up this -Papillary and reticular areas -richly provided with lymphatic vessels and a nerve supply
Skin/integument
-insulates and cushions the underlying body tissues and protects the entire body from mechanical , chemical damage, thermal damage, and bacterial invasion;prevents water loss; regulates heat loss; mini-excretory system; chemical conversions (vitamin D synthesis); sense organs (dermis)
Papillary layer
-more superficial dermal region composed of areolar CT. Uneven and has finger like projections from its superior surface (dermal papillae- attach it to the epidermis) -lie on top of the larger dermal reidges -produce fingerprints -abundant capillary networks
keratinocytes
-most abundant epidermal cells, mainly to produce keratin fibrils
Sweat (sudoriferous) glands
-outlets for the glands are epithelial openings called pores
Apocrine
-primarily in the axillary and genital areas -secrete a milky protein and fat rich substance
Stratum Corneum (horny layer)
-the outermost epidermal layer consists of some 20 - 30 cell layers -accounts for the bulk of the epidermal thickness -dead -flattened scalelike remnants are fully keratinized -carotene
Stratum Granulosum (granular layer)
-thin layer named for the abundant granules its cells contain 1. lamellated granules - waterproofing glycolipid that is secreted into the extracellular space 2. keratohyaline granules - combine with the intermediate filaments in the more superfical layers to form the keratin fibrils
Stratum lucidum (clear layer)
-thin, translucent band of flattened dead keratinocytes with indistinct boundaries -not present in regions of thin skin -dead
_____ glands are found primarily in the genital and axillary areas
Apocrine
these cells produce a brown to black pigment that colors the skin and protects DNA from the damaging effects of UV radiation
Melanocytes
The portion of the hair that you see that projects from the scalp surface is known as the
Shaft
Melanocytes
Spidery black cells that produce the borwn to black pigment called melanin
Lunule
The proximal region of the thickened nail matrix, which appears as a white crescent (blood supply in the underlying dermis)
Hypodermis/superficial fascia
The subcutaneous tissue deep to the skin. It is not part of the skin, but it shares some of the skins protective functions. It is superficial to the tough connective tissue wrapping (fascia) of the skeletal muscles, consists mostly of adipose tissue. Functions: Anchors the skin to the underlying structures (mostly muscle), acts as a shock absorber.
(T/F) nails are hornlike derivatives of the epidermis
True
hair bulb
collection of well nourished germinal epithelial cells at the basal end of the follicle
If the environment is cool and the body heat must be conserved, the arterioles ___ so that blood bypasses the dermal capillary networks temporarily
constrict
When body temp high, the arterioles serving the skin ____ and the capillary network of the dermis becomes engorged with heated blood
dilate
hair root
enclosed within the follicle
The skin has two distinct regions. The superficial layer is the ______ and the underlying CT, the _______
epidermis; dermis
Nail bed
extension of the stratum basale beneath the nail
Sebaceous (oil) glands
found nearly all over the skin except for the palms of the hands and soles of the feet
Tactile (merkel ) cells
occasional spiky hemispheres that form sensitive touch receptors located at the epidermal-dermal junction
hair shaft
portion projecting from the scalp surface
Sebum
products of sebaceous glands -mixture of oily substances and fragmented cells that acts as a lubricant to keep the skin soft and moist and keeps hair from becoming brittle
The ducts of _____ glands usually empty into a hair follicle but may also open directly on the skin surface
sebaceous
Cutaneous glands
sebaceous glands and the sweat glands
All the following are functions of the skin except excretion of body wastes insulation protection from mechanical damage site of vitamin A synthesis
site of vitamin A synthesis
Nail Folds
skin folds that overlap border of nail
Arrector pili muscle
small bands of smooth muscle cells connect each hair follicle to the papillary layer of the dermis
Papilla
small nipple of dermal tissue that protrudes int o the hair bulb from the CT sheath and provides nutrition to the growing hair
hair
structure consisting of a medulla, a central region surrounded first by the cortex and then by the protective cuticle .
Root
the part that is embedded in the skin and adheres to an epithelial nail bed
Free edge
the portion of the nail that grows out away from the body
Eponychium
the thick proximal nail fold commonly called the cuticle
Nail Body
the visible attached portion
Nail Matrix
thickened proximal portion of the nail bed; responsible for nail growth